Various waste streams have particulate contaminants that should be removed or concentrated for proper disposal. Traditionally, ponds have been used for dewatering the sludge or slime, but ponding is undesirable due to large areas of lands needed as well as associated environmental, economic, aesthetic and safety reasons. Addition of flocculants to the waste stream can facilitate concentration of particulate wastes. In particular, phosphate mining produces clay and clay like particulates. Economic constraints drive the use of flocculants with respect to efficiency and cost of the processing.